Functional analysis to identify genes in wine yeast adaptation to low-temperature fermentation

Aims: To identify genes and proteins involved in adaptation to low-temperature fermentations in a commercial wine yeast. Methods and Results: Nine proteins were identified as representing the most significant changes in proteomic maps during the first 24 h of fermentation at low (13 degrees C) and standard temperature (25 degrees C). These proteins were mainly involved in stress response and in glucose and nitrogen metabolism. Transcription analysis of the genes encoding most of these proteins within the same time frame of wine fermentation presented a good correlation with proteomic data. Knockout and overexpressing strains of some of these genes were constructed and tested to evaluate their ability to start the fermentation process. The strain overexpressing ILV5 improved its fermentation activity in the first hours of fermentation. This strain showed a quicker process of mitochondrial degeneration, an altered intracellular amino acid profile and laxer nitrogen catabolite repression regulation. Conclusions: The proteomic and transcriptomic analysis is useful to detect key molecular adaptation mechanisms of biotechnological interest for industrial processes. ILV5 gene seems to be important in wine yeast adaptation to low-temperature fermentation. Significance and Impact of the Study: This study provides information that might help improve the future performance of wine yeast, either by genetic modification or by adaptation during industrial production.